A conventional electrophotographic image forming apparatus uses an electrophotographic image forming process. Such a conventional electrophotographic image forming apparatus employs a process cartridge system in which an electrophotographic photosensitive member and a process member used for performing processing on the electrophotographic photosensitive member are integrally assembled into a cartridge, and the cartridge is detachably attached to the image forming apparatus. With such a process cartridge system, a user can perform, in effect, maintenance of an image forming apparatus by himself without asking a serviceperson for maintenance. Accordingly, a user's operability can be significantly improved. Therefore, the process cartridge system is widely used with image forming apparatuses.
The process cartridge has a configuration such that a photosensitive member unit including an electrophotographic photosensitive member swingably supports a developing unit including a developing member and a biasing member is provided to cause the developing member to contact the electrophotographic photosensitive member. Furthermore, the developing member, which serves as a process member, contacts the electrophotographic photosensitive member with a predetermined clearance or at a predetermined contact pressure.
Laid-open Japanese Patent Application Hei 09-120251 (corresponding to U.S. Pat. No. 5,450,166) discusses a method for supporting a developing unit with a photosensitive member unit. In this method, a protruding portion of an arm portion provided at both ends of the developing unit in a longitudinal direction thereof fits in a recessed portion provided on the photosensitive member unit. The photosensitive member unit is coupled to the developing unit with a coupling member having a spring member for pressing the developing unit against the photosensitive member unit.
In addition, Laid-open Japanese Patent Application Hei 10-20745 (corresponding to U.S. Pat. No. 6,016,413) discusses a method in which a fitting shaft is press-fit in holes respectively provided in an arm portion provided at both ends of a developing unit in a longitudinal direction thereof and a cleaning frame member.